import math
x1,y1,x2,y2 =map(float, input().split())

length = math.sqrt((x2 - x1) ** 2 + (y2 - y1) ** 2)
print("{0:04f}".format(length)) import math math x1,y1,x2,y2 =map(float, input().split()) x1 map(float, input().split()) map float input().split() ().split () input split y1 x2 y2 length = math.sqrt((x2 - x1) ** 2 + (y2 - y1) ** 2) length math.sqrt((x2 - x1) ** 2 + (y2 - y1) ** 2) math.sqrt math sqrt (x2 - x1) ** 2 + (y2 - y1) ** 2 (x2 - x1) ** 2 x2 - x1 x2 x1 2 (y2 - y1) ** 2 y2 - y1 y2 y1 2 print("{0:04f}".format(length)) print "{0:04f}".format(length) "{0:04f}".format "{0:04f}" format length y2 =map(float, input().split()) map(float, input().split()) y2 y1,x2,y2 =map(float, input().split()) map(float, input().split()) y1 x1,y1,x2,y2 =map(float, input().split()) map(float, input().split()) x1 x2,y2 =map(float, input().split()) map(float, input().split()) x2 length = math.sqrt((x2 - x1) ** 2 + (y2 - y1) ** 2) math.sqrt((x2 - x1) ** 2 + (y2 - y1) ** 2) length
import math
x1,y1,x2,y2 =map(float, input().split())

length = math.sqrt((x2 - x1) ** 2 + (y2 - y1) ** 2)
print("{0:04f}".format(length))